Bladders comprising an outer film encapsulating a high viscosity fluid or gel are well known in the art. Such composite materials are disclosed, for example, in U.S. Pat. No. 5,633,282 to Chen. Such fluid-filled bladders are generally made by fusing together two layers of the film along an outer contour of the shape of the bladder, except for a fill port through which the high viscosity fluid or gel is injected into the bladder. Then, after the bladder has been filled through the fill port, the fill port is sealed. This method of forming the fluid-filled bladder greatly complicates the fabrication thereof. There is a need in the art for a method of fabricating the fluid-filled bladders without having to inject the fluid through a fill port and without having to seal or close the fill port as a separate step.
U.S. Pat. No. 2,422,979 to Pecker discloses apparatus for fabricating parts by bonding strips of material. Radio frequencies are used for sealing. Vacuum and pressure are applied to the material.
U.S. Pat. No. 2,936,816 to Lang discloses a method and apparatus for sealing thermoplastic containers using high frequency electrical energy and an electrode that moves up and down in a chamber.
U.S. Pat. No. 3,692,613 to Pederson discloses a liquid filled pouch that is sealed using an electric impulse.
U.S. Pat. No. 3,894,744 to Ranocha et al. discloses the use of a high frequency generator in an apparatus for welding shoe parts together.
U.S. Pat. No. 4,007,838 to Awad discloses a liquid sealed in a flexible bag. The bag is sealed using a heat seal.
U.S. Pat. No. 4,539,793 to Malek discloses internally burstable pouches that have material sealed in them using radio frequency energy.
U.S. Pat. No. 4,660,354 to Lancaster et al. discloses a method of filling and sealing RF-sealable packing containers.
U.S. Pat. No. 5,254,197 to Klems discloses the use of vacuum and microwave energy to produce a seat cushion.
U.S. Pat. No. 5,554,422 to Gill et al. discloses a container that is formed from a vacuum-formed top container portion and a vacuum-formed bottom container portion. The peripheral edges of the top and bottom container portions are melted by heater to form a completed container.